Application and activation of durable water repellant using a densified fluid

ABSTRACT

A pressurized system using densified fluid can apply and/or activate durable water repellant. Durable water repellant bound to fibers of an article of clothing can be activated by first removing contaminants via a pressurized densified fluid cleaning process and thereafter imputing energy into the durable water repellant via the article&#39;s interaction with the densified fluid and its gaseous rinse cycle.

RELATED APPLICATION

The present application relates to and claims the benefit of priority toU.S. Provisional Patent Application No. 61/770964 filed 28 Feb. 2013which is hereby incorporated by reference in its entirety for allpurposes as if fully set forth herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention relate, in general, to durablewater repellant and more particularly to the application and/oractivation of durable water repellant using densified carbon dioxide.

2. Relevant Background

Durable Water Repellent (DWR) is a coating added to fabrics to make themwater-resistant (or hydrophobic). The hydrophobic effect is an observedtendency of nonpolar substances to aggregate in an aqueous solution andexclude water molecules. A nonpolar substance possesses an equal sharingof electrons between the two atoms of a diatomic molecule because of thesymmetrical arrangement of the electrons. The name hydrophobic,literally meaning “water-fearing,” describes the segregation andapparent repulsion between water and nonpolar substances. Thehydrophobic effect explains the separation of a mixture of oil and waterinto its two components, and the beading of water on nonpolar surfacessuch as waxy leaves.

The hydrophobic interaction is mostly an entropic effect originatingfrom the disruption of highly dynamic hydrogen bonds between moleculesof liquid water by the nonpolar solute. A hydrocarbon chain or a similarnonpolar region of a big molecule is incapable of forming hydrogen bondswith water and accordingly the introduction of such a non-hydrogenbonding surface into water causes disruption of the hydrogen bondingnetwork between water molecules. In DWR the hydrogen bonds arereoriented tangential to a surface to minimize disruption of thehydrogen bonded 3D network of water molecules and thus creates a water“cage” around the nonpolar surface. The water molecules that form the“cage” (or solvation shell) have restricted mobility. By aggregatingsuch molecules together, nonpolar molecules reduce the surface areaexposed to water and minimize their disruptive effect. Thus watercohesion is enhanced.

The hydrophobic effect can also be quantified by measuring the partitioncoefficients of non-polar molecules between water and non-polarsolvents. The partition coefficients can be transformed to a free energytransfer that includes enthalpic and entropic components. Recall thatenthalpy is the measure of total energy of a thermodynamic system whileentropy is a measure of disorder or the number of ways that a system maybe arranged. The hydrophobic effect is entropy-driven at roomtemperature because of the reduced mobility of water molecules in thesolvation shell of the non-polar solute. However, the enthalpiccomponent of transfer energy is favorable, meaning there is astrengthening of water-water hydrogen bonds in the solvation shell,apparently due to the reduced mobility of water molecules. A solvationshell is a shell of any chemical species that acts as a solvent andsurrounds a solute species. When the solvent is water it is oftenreferred to as a hydration shell or hydration sphere. At the highertemperature, when water molecules became more mobile, this energy gaindecreases, but so does the entropic component. As a result of suchentropy-enthalpy compensation, the hydrophobic effect (as measured bythe free energy of transfer) is only weakly temperature-dependent andbecomes smaller at a lower temperature.

Historically, DWR containing long perfluoroalkyl chains have been thechemistry of choice for textile applications. Perfluorinated chemicalsare used to incorporate raw materials containing a perfluoroalkyl chaininto acrylic or urethane polymer that are used as DWR finishes. Theunique water and oil repellency properties of a DWR finish is derivedfrom the perfluoroalkyl chain that is attached to the acrylic orurethane polymer backbone. Most factory-applied treatments of DWR arethus fluoropolymer based. A fluoropolymer is a fluorocarbon-basedpolymer with multiple strong carbon-fluorine bonds. Fluoropolymers sharethe properties of fluorocarbons in that they are not as susceptible tothe van der Waals force as hydrocarbons. This contributes to theirnon-stick and friction reducing properties. Also, they are stable due tothe stability multiple carbon-fluorine bonds add to a chemical compound.Fluoropolymers may be mechanically characterized as thermosets orthermoplastics. Fluoropolymers can be homopolymers or copolymers and arecharacterized by a high resistance to solvents, acids, and bases. Whilethe present invention below is described with respect to DWR treatmentsin general and more specifically toward the use of fluoropolymers, oneof reasonable skill in the art will recognize that the innovativetechniques and associated apparatus described below are equallyapplicable to other types of fluorochemicals including perfluorooctanesulfonate (PFOS) and perfluorooctane acid (PFOA). Moreover, the presentinvention is equally applicable to short chained fluorinated DWRchemistries.

Silicon is another chemical structure often associated with waterrepellants. Silicone water repellents or waterproofing agents generallycome in two forms. Elastomeric polydimethylsiloxanes describeelastomeric coatings that adhere to a substrate and cure to form aflexible, protective membrane. Penetrating water-repellent chemicalsdescribe reactive silanes and siloxane resins with crosslinkable sidechains. These materials have smaller molecular structures, which enablethem to penetrate deeply into a substrate with which they chemicallybond.

Silicones have low surface tension, which enables them to spread andsoak easily into a substrate's pores. Their highly flexible and mobilesiloxane backbone enables the water-repelling methyl groups to orientthemselves toward the surface, creating a waterproof “umbrella” similarto fluorine based compounds. Water repellents such as DWR are commonlyused in conjunction with waterproof breathable fabrics to prevent theouter layer of fabric from becoming saturated with water. Thissaturation, called “wetting out,” can reduce the garment's breathability(moisture transport through the breathable membrane) and let waterthrough. Without DWR, even a waterproof jacket's exterior would becomewaterlogged and heavy with the damp fabric sagging and clinging to thewearer. Moreover, DWR does not inhibit breathability since DWR does not“coat” the surface, but rather bonds to the textile fibers leaving thespace between the fibers intact.

Prior methods for factory application of DWR treatments involve applyinga solution of a chemical onto the surface of the fabric by spraying ordipping. More recently the chemistry is applied in the vapor phase usingChemical Vapor Deposition (CVD) machinery. Later advances haveeliminated per-fluorinated acids, considered to be potentially hazardousto human health by the US Environmental Protection Agency, from theapplication process.

Durable Water Repellent (DWR) coatings are ubiquitous in many markets;e.g. outdoors apparel, gear, tents, etc. Typically these coatings areapplied to a textile or fabric substrate, which then becomes part of afinished product such as a jacket or parka, sleeping bag, footwear ortent, to name just a few examples. At the industrial level, when thefabric or textile is treated, DWR agents are applied via a “wet”chemistry process, and then “activated” or “energized” via heat, againvia an industrial process. The “activated” DWR treated fabric thenbecomes incorporated into a downstream-finished product (e.g. a parka).

There are several problems associated with DWR agents and with theprocess via which they are applied, “activated,” “re-applied”, and“re-activated.” The first problem is that the fluorocarbons present inDWR are bio-accumulative (i.e. they enter and remain in the bloodstreamof those exposed), and they do not degrade in the natural environment.Thus the two main DWR's currently used are considered “likelycarcinogens” by the EPA.

Additionally, the process via which they are applied is energy, time andchemically intensive, and creates a problematic secondary waste stream.Moreover, DWR coatings easily degraded, such that after repeated use ofa DWR-treated item (e.g. a jacket), and/or several wash and wear cycles,the DWR coating becomes increasingly “de-activated.” The usualmechanisms for this de-activation are oils, dirt, and particles thataccumulate and interfere with the actual DWR repellency properties at amolecular level. The resulting effect is that water repellency islessened, which affects marketability, customer satisfaction, and canimpact product warranties and/or costs.

There are home-based methods for “re-activating” and “re-coating”finished apparel with a DWR agent, however these suffer from poorperformance, poor reliability and involve long, labor and energyintensive steps necessary to “energize” the newly applied DWR, and/or“re-activate” the previously existing DWR. Accordingly, there is a needto provide a means by which to efficiently and effectively restore theDWR properties in DWR treated materials. These and other deficiencies ofthe prior are addressed by one or more embodiments of the presentinvention.

Additional advantages and novel features of this invention shall be setforth in part in the description that follows, and in part will becomeapparent to those skilled in the art upon examination of the followingspecification or may be learned by the practice of the invention. Theadvantages of the invention may be realized and attained by means of theinstrumentalities, combinations, compositions, and methods particularlypointed out in the appended claims.

SUMMARY OF THE INVENTION

A system and associated methodology for the application and/oractivation of a durable water repellant is hereafter described. Onemethod embodiment for activating durable water repellency includes,depositing within a pressure vessel an article having one or morefibers, wherein the one or more fibers of the article are bound with adurable water repellant. Thereafter the article is processed with adensified fluid to remove contaminants. With the article clean theprocess continues by energizing the durable water repellant bound to theone or more fibers of the article.

Similarly, durable water repellant can be applied to an article havingone or more fibers by depositing it within a pressure vessel and thenprocessing the article with a densified fluid to remove contaminants. Inthis case, the densified fluid includes durable water repellant insolution that binds to the fibers of the article. Once bound to thefibers the durable water repellant is energized by, in one embodiment,subjecting the article to a high-pressure gaseous rinse cycle.

The present invention further includes, according to another embodiment,a system to activate durable water repellent. Such a system can includea pressure vessel operable to hold a densified fluid athyper-atmospheric pressure, a storage tank fluidly coupled to thepressure vessel for storing the densified fluid and a distillationsystem fluidly coupled to the pressure vessel and the storage tank. Thedistillation system is operable to remove suspended and dissolvedcontaminants from the densified fluid. Lastly, the system includes anarticle having one or more fibers in which the fibers of the article arebound with durable water repellant. The interaction between the articleand the densified fluid, including the exposure to static electriccreated during a high pressure gaseous rinse cycle, within the pressurevessel energizes the durable water repellant.

In yet another embodiment of the present invention, durable waterrepellant can be applied to the fibers of an article using a system thatincludes a pressure vessel operable to hold a densified fluid athyper-atmospheric pressure wherein the densified fluid includes durablewater repellant in solution. The system can also include a storage tankand a distillation system fluidly coupled to the pressure vessel whereinthe distillation system is operable to remove suspended and dissolvedcontaminants from the densified fluid. Interaction between the articleand the densified fluid binds the one or more fibers and concurrentlyenergizes its structure.

The features and advantages described in this disclosure and in thefollowing detailed description are not all-inclusive. Many additionalfeatures and advantages will be apparent to one of ordinary skill in therelevant art in view of the drawings, specification, and claims hereof.Moreover, it should be noted that the language used in the specificationhas been principally selected for readability and instructional purposesand may not have been selected to delineate or circumscribe theinventive subject matter; reference to the claims is necessary todetermine such inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The aforementioned and other features and objects of the presentinvention and the manner of attaining them will become more apparent,and the invention itself will be best understood, by reference to thefollowing description of one or more embodiments taken in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a high-level depiction of a densified fluid cleaning systemaccording to one embodiment of the present invention; and

FIG. 2 shows a flowchart of one method embodiment for applying and/oractivating DWR using a densified cleaning system according to thepresent invention.

The Figures depict embodiments of the present invention for purposes ofillustration only. One skilled in the art will readily recognize fromthe following discussion that alternative embodiments of the structuresand methods illustrated herein may be employed without departing fromthe principles of the invention described herein.

DESCRIPTION OF THE INVENTION

DWR works by increasing the contact angle or surface tension createdwhen water contacts a textile or similar surface. Basically, a highcontact angle creates a microscopically “spiky” surface that suspendswater droplets on the outer fringe of the fabric. The result is that thewater droplets keep a rounder shape much like a domed shape bead. Therounder the droplet, the more likely it is to roll off the garment orfabric. A low contact angle conversely allows the water droplet tospread out and cling to the textile and eventually seep in. Themolecular chain present in all DWRs can be affected by physical contact(rubbing) and masked by dirt and oils. The result reduces the surfacetension and allows the water to flatten out or adhere to the fabric.

The present invention provides a simpler, faster, more effective, andless energy/chemical intensive method for activating DWR present in atextile or fabric substrate. One embodiment of the present inventionemploys dense phase (e.g. liquid or super critical) Carbon Dioxide (CO₂)as the “wet process,” specifically via a CO₂-based cleaning system inwhich the item(s) in question are processed.

Mechanisms specific to a CO₂ cleaning process employing dense phase CO₂as the principal cleaning/rinsing agent including a high pressuregaseous rinse cycle enables an enhanced DWR chemical structure resultingin an activation and/or application of DWR characteristics.

According to one embodiment of the present invention, a CO₂ cleaningmethodology includes an enhanced rinsing and distillation process thatenergizes the molecular bonds present in the DWR components. This isenabled by proper thermodynamic balance (heat transfer such as viarefrigeration) accommodated in a system designed with sufficient storagecapacity to enable continuous, real time distillation of CO₂ to separatecontaminants producing pure, uncontaminated CO₂ throughout wash & rinsecycle(s). More specifically, the continuous distillation system and CO₂processes of the present invention imputes energy into the DWRfluoropolymer and/or silicon bonds enhancing its hydrophobiccharacteristics.

Prior, early prototypes of CO₂ cleaning systems distilled CO₂ in animprecise and batched manner. Some used partial distillation whileothers did not distill the fluid at all and rather relied on filtrationas the mechanism for cleaning the CO₂. Others used a pressuredifferential for distillation.

The CO₂ purification results were poor due to various issues including:poor process flow and valve/piping designs limiting the ability tomaintain precise process control and stills that were too small tohandle the CO₂ volume of the machine. Moreover, the condensingproperties of these machines were also too low to achieve thedistillation needed to keep the needed volume of CO₂ in a clean purifiedform available throughout the entire cleaning process. The presentinvention presents a continuous distillation and rinse system that notonly produces purified CO₂ to assist in cleaning textiles, but alsoenergizes the molecular bonds between the large DWR molecules to furtherinhibit its ability to bind with hydrogen in a water molecule. As aresult, the water molecules form a water cage and bead up on the DWRtreated surface.

Another aspect of the present invention that results in an enhancedapplication and/or activation of DWR is a hi-speed extraction of CO₂ anduse of advance drive Variable Frequency Drive, (VFD) with precise speedcontrol to accelerate and enhance static electricity generation,throughout the wash/rinse process. This static charge generation throughthe introduction of a gaseous rinse cycle energizes and activates theDWR. In addition, the added pressure associated with the CO₂ cleaningprocess of the present invention adds additional energy into the DWRtreated fabric ultimately enhancing the DWR characteristics. Note thatthe present invention does not employ heat as a mechanism to “energize”and activate DWR as is applied in the prior art. So, instead of heat,which can ultimately damages the garment, the present inventiongenerates energy (e.g. static electricity) in the CO₂ extraction andreclamation cycle that re-aligns the DWR molecules to their mosteffective configuration. Due to the controlled environment embodied bythe present invention the DWR molecules are aligned into their mostefficient hydrophobic formation.

According to another embodiment of the present invention, DWR can beapplied to pre-constructed garments and/or raw or finished fabrics usingtechniques presented herein and achieve superior results at the OriginalEquipment Manufacturer (OEM) level imparting enhanced water repellencyproperties. Furthermore, embodiments of the present invention can beused to re-apply or re-activate DWR in the secondary market, within thesame system, as part of a general re-conditioning or service of garmentsor other items.

One or more embodiments of the present invention describes a closedsystem using a continuously cleaned/purified source of and/or supercritical CO₂ in a cleaning process that approximately lasts 30 minutes.As there is no secondary waste all fluorocarbons and DWR agents arecontained within a closed system and water is not used as a cleaningmedium. The process includes not only extraction of contaminates thatmay diminish DWR characteristics as described herein, but reforms(realigns) the DWR chemical structure to its optimal form through theintroduction of additional forms of energy such as static electricityand energy exchange as which occurs during decompression. Unlikeconventional cleaning and drying processes in which measures areimplemented to mitigate the production of static electricity, thepresent invention employs techniques to enhance the production of staticelectricity that thereafter energizes the DWR so as to align the polesof the DWR molecules.

Embodiments of the present invention are hereafter described in detailwith reference to the accompanying Figures. Although the invention hasbeen described and illustrated with a certain degree of particularity,it is understood that the present disclosure has been made only by wayof example and that those skilled in the art can resort to numerouschanges in the combination and arrangement of parts without departingfrom the spirit and scope of the invention.

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the present invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. Also, descriptions of well-known functions and constructionsare omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but are merely used by theinventor(s) to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention are provided for illustration purposes only and notfor the purpose of limiting the invention as defined by the appendedclaims and their equivalents.

Durable water repellent (DWR) is a textile finish whose performanceattributes (effects) may include water repellency, oil repellency, stainrepellency, soil repellency, stain release, soil release, and durability(e.g. to laundering, dry cleaning, abrasion, light exposure, rain, etc.)

Fluoropolymer is a fluorinated polymer made by (co) polymerization ofmonomers that contain fluorine to create a polymer with fluorinedirectly bound to carbons of the polymer backbone.

By the term “substantially” it is meant that the recited characteristic,parameter, or value need not be achieved exactly, but that deviations orvariations, including for example, tolerances, measurement error,measurement accuracy, limitations and other factors known to those ofskill in the art, may occur in amounts that do not preclude the effectthe characteristic was intended to provide.

Like numbers refer to like elements throughout. In the figures, thesizes of certain lines, layers, components, elements or features may beexaggerated for clarity.

The terminology used herein is for the purpose of describing particularembodiments only, and is not intended to be limiting of the invention.As used herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. Thus, for example, reference to “a component surface”includes reference to one or more of such surfaces.

As used herein any reference to “one embodiment” or “an embodiment”means that a particular element, feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment. The appearances of the phrase “in one embodiment” in variousplaces in the specification are not necessarily all referring to thesame embodiment.

As used herein, the terms “comprises,” “comprising,” “includes,”“including,” “has,” “having” or any other variation thereof, areintended to cover a non-exclusive inclusion. For example, a process,method, article, or apparatus that comprises a list of elements is notnecessarily limited to only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. Further, unless expressly stated to the contrary,“or” refers to an inclusive or and not to an exclusive or. For example,a condition A or B is satisfied by any one of the following: A is true(or present) and B is false (or not present), A is false (or notpresent) and B is true (or present), and both A and B are true (orpresent).

Unless otherwise defined, all terms (including technical and scientificterms) used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this invention belongs. It will befurther understood that terms, such as those defined in commonly useddictionaries, should be interpreted as having a meaning that isconsistent with their meaning in the context of the specification andrelevant art and should not be interpreted in an idealized or overlyformal sense unless expressly so defined herein. Well-known functions orconstructions may not be described in detail for brevity and/or clarity.

It will be also understood that when an element is referred to as being“on,” “attached” to, “connected” to, “coupled” with, “contacting”,“mounted” etc., another element, it can be directly on, attached to,connected to, coupled with or contacting the other element orintervening elements may also be present. In contrast, when an elementis referred to as being, for example, “directly on,” “directly attached”to, “directly connected” to, “directly coupled” with or “directlycontacting” another element, there are no intervening elements present.It will also be appreciated by those of skill in the art that referencesto a structure or feature that is disposed “adjacent” another featuremay have portions that overlap or underlie the adjacent feature.

Spatially relative terms, such as “under,” “below,” “lower,” “over,”“upper” and the like, may be used herein for ease of description todescribe one element or feature's relationship to another element(s) orfeature(s) as illustrated in the figures. It will be understood that thespatially relative terms are intended to encompass differentorientations of a device in use or operation in addition to theorientation depicted in the figures. For example, if a device in thefigures is inverted, elements described as “under” or “beneath” otherelements or features would then be oriented “over” the other elements orfeatures. Thus, the exemplary term “under” can encompass both anorientation of “over” and “under”. The device may be otherwise oriented(rotated 90 degrees or at other orientations) and the spatially relativedescriptors used herein interpreted accordingly. Similarly, the terms“upwardly,” “downwardly,” “vertical,” “horizontal” and the like are usedherein for the purpose of explanation only unless specifically indicatedotherwise.

Included in the description are flowcharts depicting examples of themethodology that may be used to activate DWR using CO₂. In the followingdescription, it will be understood that each block of the flowchartillustrations, and combinations of blocks in the flowchartillustrations, can be implemented by computer program instructions.These computer program instructions may be loaded onto a computer orother programmable apparatus to produce a machine such that theinstructions that executes on the computer or other programmableapparatus create means for implementing the functions specified in theflowchart block or blocks. These computer program instructions may alsobe stored in a computer-readable memory that can direct a computer orother programmable apparatus to function in a particular manner suchthat the instructions stored in the computer-readable memory produce anarticle of manufacture including instruction means that implement thefunction specified in the flowchart block or blocks. The computerprogram instructions may also be loaded onto a computer or otherprogrammable apparatus to cause a series of operational steps to beperformed in the computer or on the other programmable apparatus toproduce a computer implemented process such that the instructions thatexecute on the computer or other programmable apparatus provide stepsfor implementing the functions specified in the flowchart block orblocks.

Accordingly, blocks of the flowchart illustrations support combinationsof means for performing the specified functions and combinations ofsteps for performing the specified functions. It will also be understoodthat each block of the flowchart illustrations, and combinations ofblocks in the flowchart illustrations, can be implemented by specialpurpose hardware-based computer systems that perform the specifiedfunctions or steps, or combinations of special purpose hardware andcomputer instructions.

The hydrogen bond between water molecules is the driving force betweentwo of waters properties: cohesion and adhesion. Cohesion is the abilityof water to stick to itself. Cohesion is the driving force behind rain.Water vapor molecules join together until they reach a point in whichthe combined weight of the molecules cannot be supported by the currentatmospheric conditions. Adhesion is the ability of water to stick toother surfaces. This enables water to spread out and form a film. Whenwater comes in contact with these surfaces the adhesive forces aregreater than water's cohesive forces. Instead of water sticking togetherit spreads out.

Water also possesses a high level of surface tension forces. Surfacetension is when molecules on the surface of the water are not surroundedby similar molecules on all sides and are thus being pulled only bycohesion forces from molecules in the interior. Surface tension is whatcauses a water droplet to be round so as to cover the smallest surfacearea possible. DWR strives to decrease the adhesive forces making watermore likely to coalesce.

On a fabric surface, the DWR particle spreads to cover the fabric fibersafter it has been applied. The fluoroalkyl chains orient perpendicularto the fabric surface. It can be imagined as microscopic umbrellasconnected to the polymer backbone. This myriad of “umbrellas” creates alow surface energy shell on the fabric with a surface energy (adhesiveforce) lower than that of water or oils. Therefore, when water or oilscontact the fabric surface they do not bond with the fluoroaklyl chainpreventing the fabric from becoming wet. Water beads up having a high“contact angle.” The high surface tension forces of water, along withweak adhesion and high cohesion drives water to form beads that possessminimal contact with the DWR treated surface. The better the treatment,the rounder the beads of water. An optimized DWR finish is designed fora specific fabric based on its fiber type and fabric construction toform an array of microscopic polymer domains on the fabric surface (nota film or coating) with the fluorinated chains erect, perpendicular tothe fabric surface and close enough to one another to act like acontinuous surface. The image is a plethora of microscopic umbrellas onthe surface with the tips touching so that no water or oil can penetrateto the fibers of the fabric. Water or oil cannot spread out, forcingthem to bead up, stand up, and slide off the fabric. One skilled in therelevant art will appreciates that silicon based chemistry also orientstheir methyl groups toward the surface creating a similar array of“umbrellas.” These and other chemical structures demonstrating similarcharacteristics are equally applicable to and contemplated by thepresent invention.

To create this plethora of microscopic umbrellas, the polymer domainsmust be correctly aligned. This alignment is driven, in part, by theenergy contained within each molecule pole. One or more embodiments ofthe present invention uses a CO₂ cleaning process to impute energy tothe DWR molecule resulting in its optimal alignment of the poles andthus produces a water resistant structure. The fluoropolymer associatedwith most DWR compounds bonds with the individual fiber of a textile.These molecules tend to align themselves into a spiky perpendicularformation reducing the fabric's adhesive forces with respect to water.That is to say, when the fluoropolymer molecules (poles) are energizedthe umbrellas are all standing up with tips touching. However as timepasses, the energy within these molecules can decrease or be compromisedby foreign agents such as dirt and oil causes the umbrellas to falldown. As the molecules “lay down” their hydrophobic effect diminishes.

One aspect of the present invention is the ability to apply an initialDWR treatment. The liquid/super critical/gaseous form of CO₂ morereadily penetrates fabrics than does an aqueous solution. Accordingly,acting as a delivery agent for a fluoropolymer molecule, CO₂ can moreuniformly and deeply apply a DWR substance than conventional techniques.The DWR substance is placed into a solution with the CO₂ and introducedto the untreated fabric during a CO₂ cleaning cycle. During the normalcleaning process the DWR substance impregnates the fabric and adheres tothe fabric fibers. Depending on concentrations and durations of thecleaning cycle differing degrees of DWR application can be achieved. Asone of reasonable skill in the relevant art will appreciate, Siliconbased and fluorocarbon based DWR components are equally enhanced by theuse of the liquid/super critical/gaseous CO₂ delivery systems of thepresent invention.

According to another embodiment of the present invention and withadditional reference to FIG. 1, DWR molecules within a DWR impregnatedfabric are activated (energized) using a densified CO₂ cleaning processand apparatus. In one version of the present invention, a cleaningsystem 100 includes an agitation basket 120 and is enclosed within apressure vessel 110. The pressure vessel is coupled to variousadditional components that may be used to obtain a satisfactory andsuccessful cleaning result using a densified fluid. For example, thepressure vessel 110 can be coupled to a purge tank 160 from which agaseous form of a densified fluid can be brought to and from thepressure vessel 110 and the cleaning environment. In addition, thepressure vessel 110 can be coupled to one or more storage tanks 170 fromwhich densified fluid can be temporarily stored and supplied to thecleaning process as required.

The CO₂ cleaning system of the present invention further includes adistillation system 135 comprised of evaporation 130 and condensation140 components that converts densified fluid into its gaseous form so asto remove any suspended and dissolved contaminants in the densifiedfluid that have been eliminated from the soiled articles and thenre-condense the gaseous form of the densified fluid back into its liquidform for further use in the cleaning process. As further shown in FIG.1, densified fluid collected from the pressure vessel containing variouscontaminants gained from the soiled articles is passed through a seriesof mechanical filters 124, 128 and eventually to an evaporator 130(distiller) wherein the densified fluid is converted from its densifiedform to its gaseous form by an change in energy through control ofpressure and/or the addition of heat thereby substantially removing anysuspended and dissolved contaminants. The now clean gas is thenre-condensed into a liquid form in a condenser 140 before being passedto a storage vessel 150 for later use within the pressure vessel.

In another embodiment of the present invention the evaporator 130 of thedistillation system 135 includes an internal heat exchanger. The heatexchanger (not shown) can comprise a coil of heating elements arrangedfor heat transfer to the densified fluid. The energy source from theheating coil can be derived from various media such as but not limitedto densified fluid, steam, hot water, electricity, hot air and/orrefrigerant. In another embodiment of the present invention steam can beused as source of heat. The heating coil can also be arranged in aboiling vessel in such a way that the coil is submerged in the densifiedfluid. It is also noted that a spiral or finned coil design increasesthe heating capacity by maximizing the heating surface although oneskilled in the relevant art will recognize that other designs for a heatexchanger could be utilized to achieve the same result.

As one of reasonable skill in the relevant art will appreciate,distillation is a method of separating mixtures based on differences involatility of components in a boiling liquid mixture. Distillation is aphysical separation process and not a chemical reaction. Only when thetemperature at which the vapor pressure of the liquid equals thepressure on the liquid do bubbles form without being crushed back intosolution. At a basic level, the heating of a volatile mixture ofsubstance A and B (wherein substance A has a lower boiling point) to itsboiling point results in a vapor that contains a mixture of A and B. Theratio of A to B in the vapor however will be different than the ratio ofA to B in the liquid. In this case the vapor will possess a higherconcentration of A since A has a lower boiling point. The vapor can becondensed to a fluid form and the process repeated until liquid of adesired purity of A can be achieved.

The distillation process, gaseous rinse and introduction of staticelectricity serve to energize the cleaning environment. A portion ofthis energy is transferred to the molecular structure of the DWRmolecules bound to the fabric fibers. These now energized DWR moleculescreate a perpendicular or spikey orientation with respect to the hostfiber which diminishes the fiber/water adhesion force. Said differently,the energized DWR molecules create a water resistant surface by whichthe cohesive forces of water are greater that the adhesive forcesbetween the fiber and water. The result is that the water beads andultimately rolls off the fabric.

FIG. 2 presents a flowchart for one methodology for applying DWR to,and/or activating DWR within, an article according to one embodiment ofthe present invention. The process begins 205 with depositing 210articles within a cleaning or agitation basket. The basket, locatedwithin the pressure vessel, is manipulable to agitate the articleswithin the pressure vessel to aid in the distribution of the densifiedsolution. The agitation and manipulation of the basket enhances thepenetration of the densified solution into the articles for applicationof the DWR and/or activation of the DWR. One of reasonable skill in therelevant art will appreciate that that the articles deposited within thepressure vessel can be articles of clothing, garment or bulk textilesand fabrics which, subsequent to treatment can then be formed intogarments.

With the articles deposited within the basket of the pressure vessel thepressure vessel is sealed 220 and a densified cleaning solution isintroduced 230 within the basket. According to one embodiment of thepresent invention the densified solution is liquefied/gaseous carbondioxide (CO₂). For the purposes of the present application the termfluid and/or densified fluid is used to describe a gaseous, liquidand/or super critical state of a substance or any combination thereof.

Typically a substance can be thought of to exist in three distinctphases. These phases or states are commonly known as solid, liquid, orgas. A phase diagram is a graphical representation of the physicalstates of a substance under different conditions of temperature andpressure. A typical phase diagram has pressure on the Y axis andtemperature on the X axis. As one moves across the lines or curves onthe graph a substance's phase changes from one to the next. Moreover,the two adjacent phases of a substance can coexist or are in equilibriumon the line separating these regions. The critical point on the graph isa point in the phase diagram in which temperature and pressure are suchthat the liquid and gaseous phases of the substance areindistinguishable. Beyond this point the temperature and pressure aresuch that a merged single-phase known as is a super critical fluidexists. The distinction between fluid and gas ceases to exist beyondthis point and the substance is referred to as a super critical fluid.

Super critical fluids can diffuse through solids like a gas, anddissolved materials like a liquid. In addition, close to the criticalpoint, small changes in pressure or temperature result in large changesin density, allowing many properties of a super critical fluid to be“fine-tuned”. Super critical fluids are often used as a substitute fororganic solvents in a range of industrial laboratory processes. Ingeneral, super critical fluids have properties of both a gas and liquid;super critical fluids (and for that matter densified fluids) can includecarbon dioxide, water, methane, ethane, propane, propylene, ethanol,acetone, and ethylene. One significant characteristic of super criticalfluids is that there is no surface tension between the liquid/gas phaseboundary. By changing the pressure and temperature of the fluid, theproperties can be “tuned” to be more liquid or more gas like.

The advantages of super critical fluid extraction (compared with liquidextraction) is that extraction from the textile are relatively rapidbecause of the low viscosity and high diffusivities. Extraction can beselective to some extent by controlling the density of the medium.Moreover, depressurizing super critical fluid and allowing the supercritical fluid to return to a gas phase easily recovers the extractedmaterial. The evaporation process leaves little solid residue behind.

Changes in pressure and temperature can also change the density of asubstance such as liquid carbon dioxide. Increasing the pressure alwaysincreases the density of a material while increasing the temperaturegenerally decreases the density with some notable exceptions. Forexample, the density of water increases between its melting point at 0°C. and 4° C. As is commonly know the density of water is greater thanthat of ice.

The effect of pressure and temperature on the densities of liquids andsolids is small. The compressibility for a typical liquid or solid is10−6 bar-1 (1 bar=0.1 MPa) and a typical thermal expansivity is10−5:K−1. This roughly translates into needing around ten thousand timesmore atmospheric pressure to reduce the volume of a substance by onepercent. A one percent expansion of volume typically requires atemperature increase on the order of thousands of degrees Celsius. Sowhile the change in density of a liquid is substantially insignificant,the point at which it transitions from a liquid to a gas can besignificantly impacted by both pressure and temperature. Therefore, adensified fluid (gaseous, liquid or super critical) comprises, for thepurposes of this application, a substance or solution that, based ontemperature or pressure, varies between gaseous, liquid and a supercritical state. One of reasonable skill in the art will recognize that adensified fluid will, in its liquid state, be coexistent with a gaseousform of the fluid in areas having a free surface such as, for example,the pressure vessel.

With the pressure vessel pressurized to hyper-atmospheric pressure andthe articles within introduced to a densified cleaning solution, thearticles are processed 240 within the basket and within the densifiedsolution to remove any contaminants, oil, soil, dirt or other impuritiesthat might alter the DWR's ability. Responsive to the conclusion of thedensified fluid process a high pressure gaseous rinse is initiated 270that can impute additional energy into the articles enclosed within thebasket. The gaseous high-pressure rinse generates a substantial amountof static electricity, which activates and energizes the DWR molecules.

With the rinse completed the pressure vessel is depressurized 280 andthe activated DWR impregnated articles removed 290 ending the process.The cleaning process using densified solutions not only returns thearticle to its original condition by removing any soil or contaminantswhich may impede existing DWR characteristics, it energizes the DWRmolecules aligning their structure to form a more cohesive and effectiveresistance to water adhesion.

The densified cleaning system 100 can also be used to apply DWRcomponents to articles, garments, textiles and the like. As with theprior methodology the untreated articles are deposited 210 within thebasket of a pressure vessel. The pressure vessel is sealed 220 and thecleaning process begins.

Rather than simply introducing a densified cleaning solution to removeany contaminants and impurities from the articles, a pressurizeddensified DWR solution can be introduced 250 into the pressure vessel.As the solution cleans the article 260, the DWR component binds with thefibers of the textile so that upon completion of the cleaning process,the articles within are impregnated with the DWR molecules. One ofreasonable skill in the relevant art will appreciate that the timeduring which the articles are subjected to the DWR densified solution aswell as the DWR concentration, pressure of the vessel and temperature ofthe environment may vary so as to arrive at an optimal and desired DWRimpregnation result.

The DWR characteristics are again enhanced through the use of ahigh-pressure gaseous rinse cycle 270 that energizes and activates theDWR molecules that remain bound to the fibers of the articles within thebasket of the pressure vessel. Upon completion of the rinse the pressurevessel is depressurized 280 with the newly impregnated and activated DWRarticles being removed 290.

These and other implementation methodologies for applying and activatingDWR components can be successfully utilized by the densified cleaningsystem 100 of the present invention. These implementation methodologiesand the specifics of their application within the context of the presentinvention will be readily apparent to one of ordinary skill in therelevant art in light of this specification.

Although the invention has been described and illustrated with a certaindegree of particularity, it is understood that the present disclosurehas been made only by way of example and that numerous changes in thecombination and arrangement of parts can be resorted to by those skilledin the art without departing from the spirit and scope of the invention,as hereinafter claimed.

While there have been described above the principles of the presentinvention in conjunction with the application and activation of DWR, itis to be clearly understood that the foregoing description is made onlyby way of example, and not as a limitation to the scope of theinvention. Particularly, it is recognized that the teachings of theforegoing disclosure will suggest other modifications to those personsskilled in the relevant art. Such modifications may involve otherfeatures that are already known per se and which may be used instead ofor in addition to features already described herein. Although claimshave been formulated in this application to particular combinations offeatures, it should be understood that the scope of the disclosureherein also includes any novel features or any novel combination offeatures disclosed either explicitly or implicitly or any generalizationor modification thereof which would be apparent to persons skilled inthe relevant art, whether or not such relates to the same invention aspresently claimed in any claim and whether or not it mitigates any orall of the same technical problems as confronted by the presentinvention. The Applicant hereby reserves the right to formulate newclaims to such features and/or combinations of such features during theprosecution of the present application or of any further applicationderived therefrom.

1. A method for activating durable water repellency, the methodcomprising: depositing within a pressure vessel an article having one ormore fibers wherein the one or more fibers of the article are bound witha durable water repellant; processing the article with a densified fluidto remove contaminants; and energizing the durable water repellant boundto the one or more fibers of the article.
 2. The method for activatingdurable water repellency of claim 1, wherein the durable water repellantis a perfluoroalkyl chain.
 3. The method for activating durable waterrepellency of claim 1, wherein the durable water repellant is based onfluorine chemistry.
 4. The method for activating durable waterrepellency of claim 1, wherein the durable water repellant is based onsilicon chemistry.
 5. The method for activating durable water repellencyof claim 1, wherein the durable water repellant is fluoropolymer based.6. The method for activating durable water repellency of claim 1,wherein the durable water repellant is perfluorooctane sulfonate based.7. The method for activating durable water repellency of claim 1,wherein the durable water repellant is perfluorooctane acid based. 8.The method for activating durable water repellency of claim 1, whereinthe densified fluid is super critical carbon dioxide.
 9. The method foractivating durable water repellency of claim 1, wherein the densifiedfluid is liquid carbon dioxide.
 10. The method for activating durablewater repellency of claim 1, wherein processing includes cleaning thearticle with liquid carbon dioxide.
 11. The method for activatingdurable water repellency of claim 1, wherein energizing includessubjecting the durable water repellant to static electricity.
 12. Themethod for activating durable water repellency of claim 1, whereinenergizing includes subjecting the article to a pressurized gaseousrinse cycle imparting energy to the durable water repellant.
 13. Themethod for activating durable water repellency of claim 1, whereinenergizing includes transferring energy from the densified fluid to thedurable water repellent.
 14. The method for activating durable waterrepellency of claim 1, wherein energizing includes transferring energyfrom a gaseous rinse cycle to the durable water repellant.
 15. A methodfor durable water repellant application, the method comprising:depositing within a pressure vessel an article having one or morefibers; processing the article with a densified fluid to removecontaminants wherein the densified fluid includes a durable waterrepellant; and energizing the durable water repellant bound to the oneor more fibers of the article.
 16. The method for durable waterrepellant application according to claim 15, wherein processing includesbinding the durable water repellant with the one or more fibers of thearticle.
 17. The method for durable water repellant applicationaccording to claim 15, wherein the durable water repellant is aperfluoroalkyl chain.
 18. The method for durable water repellantapplication according to claim 15, wherein the durable water repellantis based on fluorine chemistry.
 19. The method for durable waterrepellant application according to claim 15, wherein the durable waterrepellant is based on silicon chemistry.
 20. The method for durablewater repellant application according to claim 15, wherein the durablewater repellant is fluoropolymer based.
 21. The method for durable waterrepellant application according to claim 15, wherein the durable waterrepellant is perfluorooctane sulfonate based.
 22. The method for durablewater repellant application according to claim 15, wherein the durablewater repellant is perfluorooctane acid based.
 23. The method fordurable water repellant application according to claim 15, wherein thedensified fluid is super critical carbon dioxide.
 24. The method fordurable water repellant application according to claim 15, wherein thedensified fluid is a super critical fluid.
 25. The method for durablewater repellant application according to claim 15, wherein processingincludes cleaning the article with liquid carbon dioxide.
 26. The methodfor durable water repellant application according to claim 15, whereinenergizing includes subjecting the durable water repellant to staticelectricity.
 27. The method for durable water repellant applicationaccording to claim 15, wherein energizing includes subjecting thearticle to a pressurized gaseous rinse cycle imparting energy to thedurable water repellant.
 28. The method for durable water repellantapplication according to claim 15, wherein energizing includestransferring energy from the densified fluid to the durable waterrepellent.
 29. The method for durable water repellant applicationaccording to claim 15, wherein energizing includes transferring energyfrom a gaseous rinse cycle to the durable water repellant.
 30. A durablewater repellant activation system, the system comprising: a pressurevessel operable to hold a densified fluid at hyper-atmospheric pressure;a storage tank fluidly coupled to the pressure vessel for storing thedensified fluid; a distillation system fluidly coupled to the pressurevessel and the storage tank wherein the distillation system is operableto remove suspended and dissolved contaminants from the densified fluid;and an article having one or more fibers wherein the one or more fibersof the article are bound with a durable water repellant and whereininteraction between the article and the densified fluid within thepressure vessel energizes the durable water repellant.
 31. The durablewater repellant activation system of claim 30, wherein the distillationsystem is operable to rinse the article using high-pressure gas.
 32. Thedurable water repellant activation system of claim 31, wherein rinsingthe article with high-pressure gas energizes the durable waterrepellant.
 33. The durable water repellant activation system of claim30, wherein static electricity generated by the pressure vesselenergizes the durable water repellant.
 34. The durable water repellantactivation system of claim 30, wherein the durable water repellant is aperfluoroalkyl chain.
 35. The durable water repellant activation systemof claim 30, wherein the durable water repellant is fluoropolymer based.36. The durable water repellant activation system of claim 30, whereinthe densified fluid is carbon dioxide.
 37. The durable water repellantactivation system of claim 30, further comprising an agitation basketwithin the pressure vessel and operable manipulate the article withinthe pressure vessel.
 38. A durable water repellant application system,the system comprising: a pressure vessel operable to hold a densifiedfluid at hyper-atmospheric pressure wherein the densified fluid includesa durable water repellant in solution; a storage tank fluidly coupled tothe pressure vessel for storing the densified fluid; a distillationsystem fluidly coupled to the pressure vessel and the storage tankwherein the distillation system is operable to remove suspended anddissolved contaminants from the densified fluid; and an article havingone or more fibers wherein the one or more fibers of the article bindwith the durable water repellant and wherein interaction between thearticle and the densified fluid within the pressure vessel energizes thedurable water repellant bound to the one or more fibers.
 39. The durablewater repellant application system of claim 38, further comprising anagitation basket within the pressure vessel and operable manipulate thearticle within the pressure vessel.
 40. The durable water repellantapplication system of claim 38, wherein the distillation system isoperable to rinse the article using high-pressure gas.
 41. The durablewater repellant application system of claim 40, wherein rinsing thearticle with high-pressure gas energizes the durable water repellant.42. The durable water repellant application system of claim 38, whereinstatic electricity generated by the pressure vessel energizes thedurable water repellant.
 43. The durable water repellant applicationsystem of claim 38, wherein the durable water repellant is aperfluoroalkyl chain.
 44. The durable water repellant application systemof claim 38, wherein the durable water repellant is fluoropolymer based.45. The durable water repellant application system of claim 38, whereinthe densified fluid is carbon dioxide.